Brake fluid pressure control device

Abstract

A brake fluid pressure control device is provided, and includes a main flow path for connecting, as one system, first and second wheel brakes with a master cylinder, a first reservoir, a fluid pressure adjusting member for selectively enabling the first and second wheel brakes to communicate with the master cylinder and the first reservoir, a pump for pressurizing brake fluid in the first reservoir so as to discharge the brake fluid to a junction of the main flow path and the pump. A second reservoir which is in communication with the fluid pressure adjusting member and the second wheel brake and, a directional control valve which is adapted, in a first state, to enable the master cylinder and the fluid pressure adjusting member to communicate with each other and in a second state to interrupt communication between the master cylinder and the fluid pressure adjusting member are also provided. A control unit is also provided which, at the time of traction control, sets the directional control valve to the second state and drives the pump so as to supply the brake fluid in the second reservoir to the first wheel brake through the fluid pressure adjusting member.

What is claimed is: 
     
       1. A brake fluid pressure control device comprising: a main flow path for connecting, as one system, a first wheel brake of a driving wheel and a second wheel brake of a driven wheel with a master cylinder;   a first reservoir which is provided on the main flow path;   fluid pressure adjusting means for selectively communicating the first and second wheel brakes with the master cylinder and the first reservoir, which is provided on the main flow path;   a pump which sucks and pressurizes brake fluid in the first reservoir so as to discharge the brake fluid to a junction of the main flow path and the pump;   the junction being disposed closer to the master cylinder than the fluid pressure adjusting means;   a second reservoir for storing the brake fluid, which is communicated with the fluid pressure adjusting means and the second wheel brake;   a directional control valve which is provided on the main flow path at one side of the function adjacent to the master cylinder;   the directional control valve being adapted, in a first state, to enable communication between the master cylinder and the fluid pressure adjusting means and, in a second state, to interrupt communication between the master cylinder and the fluid pressure adjusting means; and   control means, operative at the time of traction control of the brake fluid pressure control device, for setting the directional control valve to the second state and driving the pump so as to supply the brake fluid in the second reservoir to the first wheel brake through the fluid pressure adjusting means.   
     
     
       2. A brake fluid pressure control device according to claim 1, further comprising: a flow path for enabling the directional control valve and the second reservoir to communicate with each other; and   a relief valve provided on the flow path and adapted to be opened when a pressure in the flow path at a side of the directional control valve has exceeded a predetermined value;   the directional control valve connecting the flow path and the fluid pressure adjusting means in the second state.   
     
     
       3. A brake fluid pressure control device according to claim 1, wherein the second reservoir comprises: a cylinder member for storing the brake fluid, the cylinder member having a cylinder chamber in communication with the fluid pressure adjusting means and the second wheel brake; and   a piston member which is slidably fitted into the cylinder chamber in a fluid-tight state.   
     
     
       4. A brake fluid pressure control device according to claim 2, wherein the second reservoir comprises: a cylinder member for storing the brake fluid, the cylinder member including a cylinder chamber in communication with the fluid pressure adjusting means and the second wheel brake; and   a piston member which is slidably fitted into the cylinder chamber in a fluid-tight state.